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The singer-songwriter-producer, who has penned hits like CeeLo Green's "Forget You!" and B.o.B's "Nothin' on You," says he's not interested in churning out tracks for other artists like he's done in the past.

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"There's a piece of me that's no longer there — which was basically let me write a song and then sell it," Mars said in a recent interview. "That was back in the day when I was struggling and hustling to pay rent. I was selling songs for 250 bucks ... but now that I'm OK, I shouldn't treat it like a sport."

The 28-year-old, who is one-third of the production trio The Smeezingtons, has produced for Alicia Keys, Justin Bieber, Lil Wayne and Flo Rida. Mars said he now wants to collaborate organically with others — much like on his latest album, "Unorthodox Jukebox," which is nominated for four honors at Sunday's Grammy Awards in Los Angeles. His sophomore effort, released in late 2012, features Mark Ronson, Jeff Bhasker, Diplo and Paul Epworth. The album's lead single and No. 1 hit, "Locked Out of Heaven," is nominated for song and record of the year.

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He said the upbeat jam took "months and months" to create.

"People didn't see us going at each other's throats in the studio and pulling out our hair for a song like 'Locked Out of Heaven,'" he said. "Trying to get these drums right and figure out a base line. ... It being recognized in these monster categories is an extreme honor."

The crooner's other No. 1 hit, "When I Was Your Man," is nominated for best pop solo performance, while his near-double platinum album is up for best pop vocal album.

This year marks Mars' fourth nomination for record of the year; this is his third for song of the year. He won his first and only Grammy for best male pop vocal performance with "Just the Way You Are" in 2011.

Though his debut, "Doo-Wops & Hooligans," earned a nomination for album of the year, Mars said he's not disappointed "Unorthodox Jukebox" isn't competing for the top prize this year.

"I'm good, man," he said with a laugh. "If I would have asked for anything more, I'd be a jerk. I'm happy."

The singer, who was named Billboard's top artist last year and will perform at the Super Bowl halftime show on Feb. 2, will launch a tour April 18 in Honolulu. He said he isn't recording new music at the moment.

"Nope. Nothing. I'm tapped out," he said. "Of course melodies come into my head and chord changes come in, but honestly I've just been enjoying this right now."